Internal expansion brake



Sept. 28, 193.7.

K. o. BoTNl-:N

INTERNAL EXPANS ION BRAKE Filed Maroh, 1937 EN@ g4/5505,? 5'/ /farlVille! lll.

/m/e/vzlor 4 @506x672 S/m Patented Sept. 28, 1937 UNITED STATES PATENToEFlcE 2,093,996 INTERNAL EXPANSION BRAKE Karl 0. Botnen, SchofieldBarracks, Territory o! Hawaii Application March 25, 1937, Serial No.133,034

7 Claims.

(ci. 18s-10c) I (Granted under the act of March 3, 1883, as amendedApr-i130, 1928; 370 0. G. '157) This invention described herein may bemanufactured and used by or for the Government for governmentalpurposes, without the payment to me of any royalty thereon.

This invention relates to improvements in brakes and has particularapplication to brakes type which shoes may be operated either byl uidvpressure or mechanically or both, to engage the brake drum with whichthey are associated.

Still another object of the invention is to pro- 20 vide an internalexpanding brake for vehicles including means for permitting theexpanding' members of the brake vto .be removed for relining oradjusting the same without the necessity of removing the wheels from thevehicle. Briefly stated, the invention comprises a brake of theexpansion type having two independently operable applying means providedthereon lfor actuating the expansion members of the brake includingfluid pressure means operated by the usual foot pedal and mechanicallinkage means pivotally connected to a slip ring and operated throughthe emergency brake lever or an auxiliary foot pedal'. The said fluidpressure means has a f part which directly contacts the expansionmembers of the brake and the said mechanicalv means contacts theexpansion members indirect` ly through pressure platesso that theoperation of the expansion members by either of the applying means doesnotaffect the operation of the y 4.0 other applying means.

- With the above and other objects and advantages in view 'the inventionspecifically c onsists in features of construction, arrangement andoperation of parts which will hereinafter appear. For purposes ofillustration the invention will A be describedand claimed with referenceto the accompanying drawing, in which like 'members distinguish likeparts and in which:- Fig. l is a sectional side view, partly inelevation of the brake embodying the invention, and

Fig. 2 is a cross-sectional view taken on line z-z-of Fig. 1.

In my annexed drawing a supporting member is indicated at (i) and abrake drum is indicated at (2), which is adapted to be mounted on thewheels (not shown) of a vehicle and rotatable therewith. 'Ihesup'porting member (I) is mounted within the drum (2) and comprises aninwardly extending annular ange (3) having a 5 ange (4) on its lower endwhich is fixed by rivets (5) or the like to the non-rotating part of thevehicle such as the rear axle housing (6) thereof. At the inner end ofthe flange (3) an annular flange (1) is provided for a purpose which 10will hereinafter be described. A plurality of arcuate brake-shoes (8)having a curvature conforming to the inner surface of the brake drum (2)with brake linings (9) secured thereto, are symmetrically disposedaround the 15 drum in close proximity to the inner surface thereof; morespecifically the brake-shoes' (8) are T-shaped in cross-section having aweb (I0) and a iiange portion- (Il). Ihe inner arcuate surface of theflange portion (Il) is enlarged 20 and conforms to the outer surface ofthe flange (3)v of the supporting' member (l), adjacent thereto.

An annular backing vplate (I2) is removably secured to the ange (l) ofthe supporting mem- 25 ber (I) by tap screws (i3) or the like, andextends from the rear axle housing .(8) to .adjacent the outer rim ofthe drum (2), parallel tothe flange (T) of the supporting member i) Theside walls of the drum (2) and the flanges-(3) and 80 (1) of thesupporting member form an annular channel in which the brake-shoes (8)are adapted to be mounted and which may be taken therefrom .for reliningor adjusting-the samebyremoving ljthe plate (I2) thereby eliminating thenecessity 35 of 4removing the Wheels of the vehicle. In the presentinstance the braking mechanism is illustrated as associated with thetransmission shaft ofa vehicle by being attached to the rear axlehousing, but it will be understood that it 4.0v

may be applied and used in connection with either the front or rearwheels of the vehicle. Interposed between adjacent ends of thebrakeshoes (8) are transversely disposed retaining pins (i4) which areailixed at one end to the flange (1) 5 of the supporting member (l) andextend through close tting apertures provided in the removable plate(I2). The pins (i4) provide means for retaining the brake-shoes '(8) inspaced relation each other and are adapted to frictionally contacti 50with the wearing plates (l5) providedon the opposing endsof thebrake-shoes.

Thebrake-shoes (8) are normally retained in an inoperative osition bymeans vof a 'pair' of retractile spring (I6) which are loopetl'around55' the drum (2), one on each side of the flanges (I I) of the shoes andbent to engage the pins (I4) and the inner wall of the webs (I) of theshoes where they are secured in place by any suitable .means such as byclamps (I1) Jor, the like.

The uid pressure applying means of the dual system for actuating thebrake-shoes (8) comprises radially extending cylinders (Il) which aredisposed centrally of each brake-shoe and secured lto bushings (I8),screw-threadably mounted in openings (28), provided inthe ange (3) ofthe supporting member (I) and secured thereto by lock nuts or the like.The cylinders (I8) are connected in circuit with a conventional sourceof uid supply A, including a valve B, operated by the foot pedal C ofthe vehicle, by means of conduits (2i) arranged around the inner sm'faceof the flange (3) of the supporting member (I) and by a conduit (22)leading to the source of uid supply. Within each of the cylinders (I8)is a piston (23) which extends through the bushings I3) and contactswith the enlarged inner arcuate surface of thevilange (Il) of thebrake-shoes.

'Ihe mechanical means for actuating the brakeshoes comprises rocker arms(24) in the form of belly-crank levers which are pivoted at (25) to theange (4) of the supporting member .(I). One end of the-rocker-arms (24)is pivoted at (28) to links (21) which are in turn pivoted at (28) to aslip ring (23). The other or free ends of the rocker-arms (24) -areadapted to work in guide slots (3l) provided in the ilange (3) of thesupporting member (I) and are adapted to abut against operating pressureplates (3i), as at (32). The pressure plates (3i) are interposed betweenthe shoes (8) and the supporting member (I) and .are fitted around theouter end of the bushings (I3) and the pistons (23) of the huidcylinders (I8) with their inner surface engaging the iiange (3) of thesupporting member and their outer surface abutting against the enlargedarcuate inner surface of the flange (I I) of the brake-shoes (3). Theslip ring (28) is rotatably mounted on a flange (33) which is secred tothe ange (4) of the supporting member by bolts (34) or the like. Inorder to hold and guide the slip ring (28)A in position on the ange(33), lugs (3i) are provided at suitable spaced intervals around theflange. The slip ring (28) is pivoted at (38) to a link (31) which inturn is pivotally connected at (3l) to oneend of an arm (33). The arm(33) at its other end is mounted on one end of a rock shaft (4|l).\whichis` journalled through the iiange (4) of the supporting member 'Ihismovement ofthe valve causes the fluid from the source of supply A toenter the cylinders (I8) through the conduits (2l) and (22), and forcethe pistons (23) outwardly against the brakeshoes (8).Pressureisthusexertedon all ofthe pistons (23) to cause them to pressoutwardly onV the brake-shoes, to force the brake-shoes against the drum(2) ,Y whereby the revolving of the wheel of which the drumforms a partwill ter-clockwise direction, as indicated by the arrow.

be checked or stopped depending upon the pressure exerted by the pistons(23) on the brakeshoes.

To release the brakes, the foot-pedal C is relieved of pressure by thefoot, thus opening the genoy brake lever of the vehicle to which it isto be connected and has been rotated in a clockwise i direction asindicated by the arrow, the link (31) pivoted thereto pulls on the slipring (29) which is caused to rotate on the ange (33) in a counposition.

It will thus be seen that there is provided a dual mechanism foractuating expanding brakes including both fluid pressure and mechanicalmeans which may be operated either in conjunction with or independentlyof each other and in which the brake-shoes maybe removed from the brakedrum for relining or adjusting the same without the necessity ofremoving the wheels from the vehicle.

.Although in the foregoing certain elements have been described as bestadapted to perform the functions slotted to them, nevertheless it is tobe understood that various minor changes such as causingthe pistons ofthe iluid cylinders of the duid pressure means to engage the ends of thebrake-shoes instead of the center thereof as illustrated, may beresorted to without sacriiicing any of the principles of the invention.

Having described my invention, what I claim 'as new and wish to secureby Letters Patent is:

1. In an internal expanding brake. a supporting member, a brake drum, aplurality of arcuate shoes for engagement with said drum, pressureplates engaging the arcuate inner surface of saidV slices, huid pressuremeans mounted on said supporting member and adapted to actuate saidshoes directly and mechanical means for actuating said shoes indirectlythrough said pressure plates, said mechanical means comprising commoncontrol. means, separate means connected to said common control meansfor moving each of said pressure plates against said brake shoes andmeans connected to said common control means and operable from a pointoutside the drum to operate said common control and separate means forexpanding said shoes indirectly through said pressure platesindependently -of the fluid pressure' means.

llnaninternalexpandingbrakaaslworbing member, a brake drum, a pluralityofv armate shoes for engagement with said drum, pressure plates ensuingthe arcuate inner surface of said shoes,'iiuid pressure means mounted onsaid sup- 75 porting member and adapted to actuate said shoes directlyand mechanical means for actuating said shoes indirectly through saidpressure plates,'said mechanical means comprising a ange secured to saidsupporting member, a slip ring rotatably mounted on said iiange', aplurality of rocker arms pivotally' connected to said supporting member,one of each of said rocker arms adapted to move one of each of saidpressure plates into contacting engagement with said shoes, linksconnecting each of said rocker-arms to said slip ring and meansconnected to said slip ring and operable from a point outside the drumto rotate said slip ring upon said flange to actuate said rocker armsinto engagement with said pressure plates.

` 3. In an internal expanding brake, a supporting number, a brake drum,a plurality of arcuate shoes for engagement with said drum, pressureplates engaging the arcuate inner surface of said shoes, fluid pressuremeans mounted on said supporting member and adapted to actuate saidshoes directly and mechanical means for actuating said shoes indirectlythrough said pressure plates, said mechanical means comprising a angesecured to said supporting member, a slip ring rotatably mounted on saidange, a plurality of rocker arms pivotally connected to said supportingmember, one of each of said rocker arms adapted to move one of each ofsaid pressure plates into contacting engagement with said shoes, linksconnecting each of said rocker arms to said slip ring,

f means connected to said slip ring and operable from a point outsidethe drum to rotate said slip ring upon said flange to actuate saidrocker arms into engagement with said pressure plates'and means toretract said brake shoes, A

4. In an internal expanding brake, a supporting member, a brake drum, aplurality of arcuate shoes for engagement with said drum, pressure.

member-y a' 'brake drum, a plurality of arcu-` ate shoes for engagementwith said drum, pressure plates engaging the arcuate inner surface lofsaid shoes and two independently operable applying means for actuatingAsaid shoes, one of said means comprising a source of fluid supply, aplurality of cylinders in communication with said source o f uid supplyand mounted on said sup- 5 'porting member, a piston provided in each ofsaid cylinders and adapted to eng'age one of each of .said shoesdirectlyand the other of said means engaging said shoes indirectlythrough said pressure plates, said pressure plates tted around the shoeengaging' portion of said pistons. 6. In an internal expanding brake, asupporting member, a' brake drum, a plurality of Aarcuate shoes forengagement with said drum, pressure plates engaging the arcuate innersurface of said shoe-'sand two independently operable applying means foractuating said shoes, one of said means comprising a source of fluidsupply, a plurality of cylinders in communication with said source ofsupply and mounted on said supporting member,

20 a piston in each of said cylinders and adapted to lxengage thearcuate inner-surface of said shoes directly and the other of said means.operating said` shoes indirectly through said pressure plate and meansto retract said shoes.'

'1. In an internal expanding brake, a supporting member, a brake drum, aremovable plate secured to said supporting memberA and closing an openend of said drum, a plurality of spaced pins secured to said supportingmember, a plurality of arcuate shoes mounted Within said drum, forengagement with the inner surface thereof, the opposing ends of saidshoes adapted to frictionally engage one of each of said pins,retracting springs having portions adapted to engage said pins andshoes, pressure plates engaging the arcuate inner surface of said shoesand mechanical l means 'for moving -said shoes into engagement with saiddrum indirectly through said pressurel plates, said means comprising aange secured to said supporting member, a slip ring rotatably mounted onsaid flange, a plurality of rocker arms pivotally connected to saidsupporting member, one of each of said rocker arms adapted to move oneof each of said pressure plates into contacting engagement with saidshoes, links connectingeach of said rocker arms to said slip ring andmeans connected to said slip ring-and oplerable froma point outside thedrum to rotate said slip ring on said ange to actuate said rocker rockerarms into engagement with said pressure platesw KARL o, Bo'rNnN.

